Latent catalyst effects were investigated to improve the physical properties of halogen-free epoxy molding compounds (EMCs) for semiconductor encapsulation. In this study, biphenyl-type resins were used as the epoxy and hardener resin for halogen-free EMCs to obtain high flame-retardant properties and high filler contents. Latent catalyst effects were examined with two kinds of EMC compositions, halogen-free EMCs and conventional EMC compositions. We used triphenylphosphine-benzoquinone salt (TPP-BQ) as a latent catalyst. Spiral flow and gel time were measured to investigate the change in moldability with the latent catalyst. We measured package fail, moisture absorption, and delamination for reliability evaluation and flexural strength, flexural modulus, and adhesion for mechanical properties to examine latent catalyst effects. An improvement in moldability, reliability, and the mechanical properties were observed in two types of halogen-free EMCs with TPP-BQ as a latent catalyst. These phenomena were seen in conventional EMCs, including o-cresol novolac epoxy resin. The cure kinetics of these systems were investigated by differential scanning calorimetry with an isothermal approach to explain these phenomena. The results indicate that the improvement in moldability in halogen-free EMCs with TPP-BQ was due to the low conversion rate of this system, and the increase in mechanical properties was attributed to the high conversion of curing reaction.

ABSTRACT:The change of physical properties of an epoxy-molding compound (EMC) for semiconductor encapsulation according to the coupling treatment process change was investigated. Three different coupling treatment processes were applied in this study: the pretreatment method (PM), the internal pretreatment method (IPM ), and the integral addition method (IAM). Especially, we suggested a simple and economic process, the IPM process, in which the drying and powdering process is excluded compared with the PM process. The optimum content range of the coupling agent is 1.0-2.0 wt % based on the weight of the filler, which is about a 1.3-2.5 coating layer. The flexural strength and internal stress of EMC made by the IPM process is almost equivalent to that made by the PM. We applied the model of complex layers of a silane coupling agent at the filler/ matrix interface in interpretating the mechanical and thermal properties of EMC and obtaining the relationships between physical properties and the coupling process. It can be concluded that the IPM process is an effective and economic process to be able to obtain a good reliable EMC with strong mechanical strength and low internal stress.

No abstract

No abstract

Background: In this study, we performed a biomechanical tests on the osteoporotic femoral heads to validate whether the bone mineral density (BMD) measured at the non-fractured contralateral hip can predict the BMD and potential medial migration of helical blade-type lag screws on the fractured femoral head.Methods: Twenty-four osteoporotic femoral heads were retrieved from patients with femoral neck fracture undergoing hip arthroplasty. The patients had their BMD measured from the contralateral hip using dual-energy X-ray absorptiometry prior to surgery. The BMD of the retrieved femoral heads was measured using micro-computed tomography. The mechanical properties for the medial migration of lag screw were measured by performing an uniaxial compression test on the femoral head using a helical blade-type lag screw. Statistical analysis was performed to determine the correlation among the BMDs of the non-fractured contralateral hip and the retrieved femoral head and the mechanical properties of the fractured femoral head.Results: The mean BMD of the contralateral hip was 0.60±0.14 g/cm2 in the neck region and 0.63±0.15 g/cm2 in the total proximal femur. The mean BMD of the fractured femoral head was 463.3±48.05 mg HA/cm3. The mechanical properties of the fractured femoral head were measured to be 0.92 kN for the maximum compressive load and 14.50±5.48 kN for the accumulated compression load. In the analysis of the correlation among the parameters, we found no correlation between the BMD of the non-fractured contralateral hip and the mechanical properties of the fractured femoral head. In addition, we observed no correlation between the BMD of the fractured femoral head and that of the contralateral hip.Conclusions: Our results indicate that the BMD of the contralateral hip does not reflect the BMD or the mechanical properties of the fractured femoral head. Therefore, helical blade-type lag screw migration may not be predicted from the BMD of the non-fractured contralateral hip.